Accident Overview
On April 18, 2016, at approximately 1530 Eastern daylight time, a Piper PA-28-161, registration N151DC, was substantially damaged in an accident near Okeechobee, Florida. The pilot, who was the sole occupant, sustained minor injuries. The airplane was being operated as a solo instructional flight under Title 14 Code of Federal Regulations Part 91.
Engine Failure
According to the operator, while the airplane was at about 3,000 feet mean sea level, the engine suddenly began running roughly, accompanied by abnormal noises. The engine instruments remained within normal ranges. The pilot executed the “engine roughness” checklist in an attempt to troubleshoot the issue but was unsuccessful.
Shortly after, the pilot contacted the Miami Air Route Traffic Control Center to report the problem. A controller suggested diverting to St Lucie County International Airport (FPR) in Fort Pierce, Florida, where emergency services would be standing by. However, about 10 seconds after completing the checklist, the engine lost all power.
Forced Landing
The pilot established best glide speed and selected a private grass strip for a forced landing. He then performed the “engine power loss in flight” checklist, which did not restore power. Once committed to landing, he completed the “power off landing checklist.” After touchdown, the airplane skidded, struck farm equipment and other obstacles, and finally came to rest against a building.
Maintenance History
A review of the engine’s maintenance records showed that it had accumulated 10,382.8 total flight hours and 2,600.8 hours since its last overhaul. The engine manufacturer’s recommended time between overhauls was 2,400 hours.
Postaccident Examination
Examination of the airplane revealed substantial damage to the fuselage and tail section, and both wings were sheared off. During the engine examination, a hole was found in the crankcase above the No. 2 cylinder. Metal particles were present in most folds of the oil filter and in the No. 3 and No. 4 cylinders. Ferrous and nonferrous materials were found throughout the crankcase.
A compression check showed that the No. 3 cylinder had excessively low compression, and its piston did not move when the crankshaft was manually rotated. After removing the No. 3 cylinder, only the connecting rod and piston pin remained. The interior of the No. 3 cylinder was extensively damaged.
Metallurgical Findings
Metallurgical examination of the No. 3 piston revealed that it was fractured, with two fatigue cracks originating from the outer face of a lubricating hole in a compression ring groove. Areas outside the fatigue crack regions had a rough texture and on-slant planes consistent with overstress separation. The reason for the initiation and propagation of the fatigue cracks could not be determined.